The Vorpal Blade

This weapon may only be wielded by Mars.
Melee attacks made with this weapon always
hit, but do not always damage the enemy.
A unit equipped with this weapon makes
melee attacks by making either a SWOLE
roll or an Opposed SWOLE roll (ask the GM).
If your result is a partial success or you win the
opposed roll, deal normal damage.
If the result is a full success, or your opposed
roll exceeds the opponent's by 3 or more, deal
extra damage instead.